[0001] This invention relates to a valve which is suited for use with a hydraulically activated device such as a rock bolt, a prestresser, an energiser etc. These products are given by way of example only and do not limit the scope of the invention.

[0002] A device such as a prestresser is placed in an operative mode, during installation, by hydraulically inflating a volume in the device using, for example, water under pressure. The device, when correctly inflated, places stress on a rock surface against which the device reacts. This can give rise to unpredictable rock displacement, an event which poses danger to personnel in the vicinity of the device.

[0003] Another factor is that, for this type of device to be effective, it must be pressurised to a predetermined level. Due to environmental and other conditions, costs constraints and the like, it is not always easily possible in a cost-effective manner to ensure that a device has been correctly internally pressurised. [0004] An object of the present invention is to address, at least to some extent, the aforementioned factors.

SUMMARY OF THE INVENTION

[0005] The invention provides a valve for use with a hydraulically activated device which includes a stud, a coupler member, and a retentive arrangement, wherein the stud comprises a body which, in use, is attached to the device, a passage through the body which has a valve seat and which is placed in fluid communication with an interior of the device, and a valve member, inside the passage, which is movable into engagement and out of engagement with the valve seat, the coupler member including a component which is connectable to a pressurised fluid source and a fluid path through the component, and wherein the retentive arrangement secures the component to the body whereby the fluid path is placed in communication with the passage and at least one volume is formed, at least partly between opposing surfaces of the component and the body, and wherein at least part of the retentive arrangement breaks, allowing the component to become detached automatically from the body, when the pressure in the volume reaches a predetermined value.

[0006] The coupler member may include at least one reaction surface, bounding at least part of the volume, against which pressurised fluid in the volume exerts a force which is dependent on the pressure of the fluid. It is this force which can cause at least part of the retentive arrangement to break.

[0007] The stud is positioned, in use, so that an outlet from the passage is aligned with a hole through a wall of the device.

[0008] The stud may be secured to the wall of the device in any appropriate way, for example by means of a welding process. [0009] The component of the coupler member may be engageable with a connector which, in turn, is connected to the pressurised fluid source. The component may include a formation, of a conventional shape, which is engageable with the connector.

[0010] In an alternative form of the invention the component acts as a connector and directly connects the stud to the pressurised fluid source.

[0011] At least one seal may be located between opposing surfaces of the body and of the component. The seal may extend circumferentially around the body and bear against an opposing inner surface of the component. The seal may be of any suitable kind and for example may be an O-ring seal. [0012] The retentive arrangement may include at least one shear member. This shear member which, for example, is in the form of a pin, may be engaged with complementary formations in or on the body and the component. For example the shear member may extend through an aperture in the component of the coupling member and into a recess or any other suitable formation provided in the body of the stud. Use may be made of two or more shear members which are substantially identical to one another. Each shear member may then break or shear when the pressure in the volume reaches the aforementioned predetermined value.

[0013] In one form of the invention it is possible to replace a broken member with a fresh member so that the retentive arrangement is reusable. [0014] In a different form of the invention the body has at least one undercut formation and the retentive arrangement includes at least one retentive formation which may be formed integrally with the component, or which otherwise may be attached to the component, and which is engageable with the undercut formation. The undercut formation and the retentive formation then make up the retentive arrangement. The component may for example include at least one hook formation which is engageable with the undercut formation and which breaks when the pressure in the volume reaches the predetermined value.

[0015] The undercut formation may take on any suitable form. In one example of the invention the undercut formation is in the nature of a groove or channel which extends circumferentially around the body. The retentive arrangement may then include a rib formation, which is integral with the component or which is attached to the component, which may be of complementary shape, at least partly, to the groove, and which is engageable with the groove. This type of engagement may be effected by deforming at least part of the component radially outwardly so that the rib formation can ride over material of the body adjacent the groove and then spring into the groove under the natural resilience of the material from which the component is made.

[0016] To facilitate deformation of the component, as aforesaid, the component may include a skirt which in use surrounds at least part of the body. The skirt may be formed with a plurality of slits which allow sections of material between the slits to be moved radially outwardly, at least to a limited extent, without breaking. A surface of the skirt which directly opposes the body of the stud may then have the rib formation. The rib formation may comprise a plurality of segments with each segment extending between a respective adjacent pair of slits.

[0017] To prevent unintended detachment of the coupler member from the stud, use may be made of a sleeve which surrounds at least part of the component and which functions to retain the rib formation or the rib segments, as the case may be, engaged with the groove. Consequently the rib formation or rib segments can only become disengaged from the groove when the rib formation, or each rib segment, breaks or otherwise is sufficiently deformed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The invention is further described by way of examples with reference to the accompanying drawings in which :

Figure 1 illustrates from one side and in cross section a valve according to one form of the invention,

Figure 2 shows, on a different scale, the valve of Figure 1 engaged with a prestressing device,

Figure 3 shows a valve according to a second form of the invention, from one side, Figure 4 shows the valve of Figure 3 from one side and in cross-section,

Figure 5 is an exploded view of a valve according to a third form of the invention, Figure 6 is a side view of the valve in Figure 5, in an assembled configuration, in cross- section and on an enlarged scale, Figure 7 is a perspective view of a component for use in a valve according to another form of the invention,

Figure 8 shows the component of Figure 7, from one side and in cross-section, engaged with a stud of a valve,

Figure 9 shows on an enlarged scale a portion of the valve which is included in a circle marked 9 in Figure 8, and

Figure 10 shows on an enlarged scale a portion of the arrangement shown in Figure 9 enclosed in a circle marked 10.

DESCRIPTION OF PREFERRED EMBODIMENTS [0019] Figure 2 of the accompanying drawings shows a valve 10 according to a first form of the invention attached to a hydraulica!ly activated device 12, such as an energiser, a rock bolt, a prestresser or the like. These are exemplary applications only and are non-limiting. These devices are generally known in the art.

[0020] Figure 1 shows the valve 10 in cross-section and from one side, on an enlarged scale. The valve includes a stud 4 and a coupler member 16.

[0021] The stud 14 has a body 18 which is made from metal and which has a tubular construction. A fluid passage 20 extends through the body 18 from a fluid inlet 22 to a fluid outlet 24. The body 18, around the outlet 24, is shaped so that the body can readily be projection-welded to an outer surface 26 of a wall 28 of the device 12. The outlet 24 is directly in communication with an aperture 30 which extends through the wall 28 and which leads into an interior 32 of the device 12.

[0022] The body 18 has a circumferentially extending groove or channel 34 in an outer surface 36. [0023] The coupler member 16 comprises a component 40 which is made from a material which is weaker than the material from which the body 18 is made, or from an injection-moulded plastics material. The component 40 has a tubular skirt 42 which is shaped to fit closely over an end 44 of the body 18, surrounding the inlet 22. The skirt has a retentive formation comprising an inwardly extending rib 48, which acts as a hook formation, which is engageable with the groove 34. The skirt is sufficiently flexible so that when the component 40 is urged axially towards the stud body 18, as is indicated by means of an arrow 50 in Figure 1 , the skirt flares outwardly to allow passage of the rib over the end 44. The end is tapered to facilitate this type of movement. Once the rib reaches the groove 34 the skirt 42, under the inherent resilience of the material from which it is made, crimps inwardly and the rib then engages securely with the groove. A tight fit is established over a region 54 between the end 44 and an opposing surface of the component 40.

[0024] The component 40 has an undercut coupling formation 58 of conventional form which enables a connection from a pressurised fluid source, which is used to inflate the device 2, to be established in a conventional manner. [0025] A fluid flow-path 62 extends through the component 40 to the inlet 22.

[0026] The component 40 has a reaction surface 66 which opposes a surface 68 of the body 18, around the inlet 22. A small volume 72 is defined between these opposing surfaces. An O-ring seal 76 is located between the surface 66 and the surface 68. The seal can be attached to the component 40 or to the stud body 18. The seal seals the volume 72 so that liquid under pressure, inside the flow-path 62 or in the fluid passage 20, cannot escape through an interface between the component and the body.

[0027] A valve member 80 is positioned inside the fluid passage 20. The valve member has a sealing surface 82 which opposes a valve seat 84 at one end of the passage.

[0028] When the device 12 is to be activated a connector, not shown, at one end of a hose which leads from a source of pressurised water, is connected in a conventional manner to the undercut formation 58 on the coupler member. Water can then flow along the flow-path 62 into the fluid passage 20. The valve member 80 is then displaced away from the inlet 22 and the valve seat 84 and water can enter the interior 32 of the device 12.

[0029] The pressure of the water inside the device 2 is substantially the same as the pressure of the water inside the fluid passage 20 and of the water inside the flow- path 62. This pressure prevails in the volume 72 and establishes a force on the reaction surface 66 which is dependent on the area of the reaction surface and on the magnitude of the pressure.

[0030] The coupler member 16 is initially held firmly adhered to the stud by the retentive arrangement formed by the engagement of the rib 48 with the groove 34. However, the material of the component 40 and the strength of the attachment formed by engaging the rib with the groove, are carefully determined so that the rib 48 shears or breaks when the force on the reaction surface 66, which at all times urges the coupler member away from the stud in a direction 90, reaches a predetermined level which is linked to a desired inflation pressure of the device 12. At this pressure level retentive arrangement fails, and the coupler member is immediately and automatically detached from the stud. Further pressurisation of the device 2 is thereby stopped. An operator then closes off the supply of water to the valve 10. The high pressure prevailing inside the device 12 forces the valve member 80 into engagement with the valve seat 84 and the valve is thereby automatically sealed.

[0031] In this embodiment of the invention, the retentive arrangement is formed by suitably shaped and interengaged formations which are integral, respectively, with the stud 14 and the coupler member 16.

[0032] As the coupler member is automatically detached from the stud when the device 12 is correctly pressurised, it is not possible for the device to be further pressurised. Thus, the detachment of the coupler member from the stud is taken as an indication that the device 12 has been correctly pressurised. [0033] Detachment of the coupler member from the stud takes place automatically, without user intervention. Thus an operator, who is several meters away from the device, can inflate the device without being exposed to the danger of rock being displaced from a rock surface which is stressed by the device 12 as it is inflated. [0034] When the coupler member is detached from the stud an abrupt pressure change occurs in the hose which is connected to the valve. This can be sensed automatically and, in response thereto, the water supply through the hose can be automatically and quickly terminated. To prevent the hose from flapping, the hose could be tied lightly to the device 12 or to other structure. [0035] Figure 3 illustrates a valve 10A in an exploded configuration while Figure 4 shows the valve 10A from one side and in cross-section in an assembled configuration. The valve 0A has a number of similarities to the valve 10 and consequently like reference numerals (with a suffix A) are used in Figures 3 and 4 to designate components which are the same as, or similar to, corresponding components shown in Figure 1.

[0036] It has been found, during assembly of the valve 10, that when the component 40 is engaged with the stud, the skirt 42, which must flare outwardly to enable the rib 48 to engage with the groove 34, can be weakened to an extent which can cause the coupler member to become detached from the stud, when the pressure, inside the volume 72, differs meaningfully from the design pressure. The construction of the valve 10A shown in Figures 3 and 4 is aimed at avoiding this problem. The component 40A of the coupler member has a skirt 42A which has a plurality of slits 100 spaced from one another in a circumferential direction around the skirt. The retentive rib formation 48A is, however, not continuous but is divided into a number of segments, with each segment being positioned between a respective adjacent pair of slits 100. The skirt 42A has a wall thickness 02, see Figure 4, which allows the skirt to flex sufficiently and with ease so that the segments of the rib 48A can slide over an outer surface 36A of the stud and then slip into engagement with the groove 34A, which extends circumferentially around the body of the stud. Flexing of the skirt occurs without any meaningful adverse effect on the strength of the skirt - this is due to the effect of the slits 100. [0037] In order to maintain the coupler member 16A engaged with the stud in accordance with design criteria a sleeve 104, in the form of a short cylinder, is placed circumferentially over the coupler member, as shown in Figure 4, and is then pushed towards the device 12 until a leading edge 106 of the sleeve abuts a shoulder 08 on a base portion 1 0 of the stud body. [0038] The sleeve 104 has sufficient strength to prevent the skirt from opening radially outwardly when the volume 72A is pressurised. The coupler member can therefore only become detached from the stud when the rib segments shear. This occurs when the pressure in the volume 72A is at a designed value.

[0039] In this embodiment of the invention the retentive arrangement therefore includes the retentive rib (in the form of a number of segments), the groove which engages with the retentive rib, and the restricting sleeve. [0040] Figures 5 and 6 illustrate a valve 10B according to another form of the invention wherein a retentive arrangement, which makes use of shear pins, replaces the rib and groove structures of Figures 1 and 4 respectively. Where applicable, like reference numerals (with a suffix B) to those employed in Figures 1 and 2 are used in Figures 5 and 6 to indicate like components. The following description is thus confined primarily to aspects of the construction and operation of the valve 0B which are different from aspects of operation and construction of the valve 10.

[0041] A stud 14B has a body 18B through which extends a fluid passage 20B. A valve member 80B is positioned inside an enlarged portion of the passage and opposes a valve seat 84B. The stud body includes a neck 120, between the valve seat and an inlet 22B to the fluid passage in which two diametrically opposed recesses 122 and 124 are formed. A coupler member 16B fits over the neck 120. An O-ring seal 76B bounds a volume 72B at one end of a fluid flow-path 62B which goes through a component 40B of the coupler member 16B. [0042] The component 40B has a cylindrical wall 128 through which two diametrically opposed passages 130 and 132 are formed. When the component 40B is correctly engaged with the neck 120 the passages 130 and 132 are brought into direct register with the recesses 122 and 124 respectively.

[0043] Two shear pins 134 and 136 respectively are then passed through the respective passages 130, 132 and are engaged with the recesses 122, 124. The pins are slightly oversized so that when they are pushed home, as shown in Figure 6, they are tightly frictionally engaged with the passages and cannot readily be removed from the passages.

[0044] The valve 10B is used in a conventional manner. This aspect is not further described herein. When the fluid pressure inside the volume 72B reaches a predetermined level the pins 134 and 136 shear and the coupler member 16B is automatically and immediately detached from the stud 14. In this embodiment the retentive effect is achieved by using shear pins which secure the coupler member to the stud. The size and material (strength) of the pins can be varied to achieve different pressures at which the pins shear. [0045] Figure 7 shows a component 40C which is used to connect a hose from a pressurised water source directly to a hydraulically activated device, not shown. Referring as well to Figures 8, 9 and 10 the component 40C includes a fluid flow-path 62C which opens into a cavity 130 which is shaped to fit directly over a stud 14C which, in turn, is fixed to the body of the device (not shown) which is to be pressurised. [0046] The component 40C is formed with three sets of short passages 140. These are arranged in pairs so that a passage 140 diametrically opposes a passage 140X. Each passage is loaded with a respective shear member 142 which is in the form of a T-shaped shear pin (in cross-section) with an enlarged head 144 and a centrally positioned limb 146. The head is located with a close sliding fit inside a respective passage 140. [0047] A leading end of the limb 146, which protrudes through an aperture 148 at a base of the passage 140, has a tapered surface 150. The pin is biased radially inwardly, inside its respective passage, by means of a coil spring 154 which is retained in position, inside the passage, by means of a grub screw 156 or any other appropriate fastener.

[0048] The component 40C fits over the body of the stud 14C. Use can be made of an O-ring seal 160, shown only in Figure 10, between opposing surfaces of the component and of the body to seal this interface. The tapered surface 150 of each locating pin is orientated so that when the component is engaged with the stud, the tapered surface 150 rides over a corner 164 of the body of the stud. The spring 154 is then compressed in a radial outward direction. When the pins reach an undercut formation or groove 166 in the body of the stud they automatically slip into position to secure the component 40C to the body of the stud.

[0049] The fluid flow-path 62C is thereby brought into fluid communication with a passage 20C through the stud. The device to which the stud is fixed can therefore be pressurised by allowing water under pressure to flow into the device.

[0050] A volume 72C is formed between an outer face of the body of the stud and a surface of the component which surrounds the fluid flow-path. When the pressure inside this volume reaches a predetermined value the force which is exerted by the water on a reaction surface 66C causes the locating pins to shear and the component 40C breaks free from the stud, automatically. A valve member in the stud then seals the device under pressure.

[0051] In this form of the invention the retentive effect is provided by the pins which, preferably, are separately biased into engagement with corresponding formations in the stud.

[0052] The locating pins in the component 40C can be used in pairs, in succession with different devices. If all six pins have been sheared then the grub screws 156 are loosened and new pins are inserted into the passages.

[0053] In this embodiment the component 40C is directly connected to a hose which extends from a pressurised water source. Another possibility is to form the component 40C with threads 170, see for example Figure 8, and engage the threaded component with a suitable threaded socket which is permanently connected to a hose which extends from a water source. Fresh components can then be engaged with the socket, as required. Each component can be removed from the socket rapidly and fitted with new locating pins for reuse as necessary.

[0054] Each of the valves possesses the advantages which have been referred to hereinbefore.